Association between oral contraceptive use and thromboembolism: a new approach to itsinvestigation based on plasma fibrinogen chromatography.

Longitudunal and cross-dectional blood coagulation studies were made in patients receiving oral contraceptive therapy and in unmedicated women used as control subjects. These studies have included use of a new procedure, plasma fibrinogen chromatgraphy, which, by assay for a high molecular weight fibrinogen complexes in plasma, detects or excludes the presence of small thrombi, even when these are of the clinically silent type. New contraceptives users (n=154) received either Ovulen (100 pg of mestranol) or Demulen (50pg of ethinyl estradiol) and were followed serially for one year. During the cross-sectional study (193 women and 1,350 samples), serial examination was preformed on those taking oral contraceptives for 3 months to 10 years. Over-all, pathologic plasma fibrinogen chromatographic findings, indicative of thrombosis, were detected in 6 per cent of hte control examinations and in 27 per cent samples from oral contraceptive users. These findings suggest that oral contraceptive users developed mainlyclinically silent thrombotic lesions, with four-to-fivefold greater frequency than the control subjects. Consequently, it is inferred that they are at four-to fivefold greaterrisk of developing clinically overt disease, a risk factor estimate in line with that derived by epidemiologic study.